System and methods for tracking robotically controlled medical instruments

ABSTRACT

Systems and methods are described herein for tracking an elongate instrument or other medical instrument in an image.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/649,522, filed Jul. 13, 2017, which is a continuation of U.S. patentapplication Ser. No. 14/663,021, filed Mar. 19, 2015, which is acontinuation of U.S. patent application Ser. No. 13/835,698, filed Mar.15, 2013, entitled “SYSTEMS AND METHODS FOR TRACKING ROBOTICALLYCONTROLLED MEDICAL INSTRUMENTS,” the contents of each of which arehereby incorporated in their entirety by reference.

TECHNICAL FIELD

The disclosure relates generally to medical instruments, such aselongate steerable instruments for minimally-invasive intervention ordiagnosis, and more particularly to methods, systems, and apparatus forcontrolling or tracking the location, position, orientation or shape ofone or more parts of a medical instrument using registration techniques.

BACKGROUND

Currently known minimally invasive procedures for diagnosis andtreatment of medical conditions use shapeable instruments, such assteerable devices, flexible catheters or more rigid arms or shafts, toapproach and address various tissue structures within the body. Forvarious reasons, it is highly valuable to be able to determine the3-dimensional spatial position of portions of such shapeable instrumentsrelative to other structures, such as the operating table, otherinstruments, or pertinent anatomical tissue structures. Such informationcan be used for a variety of reasons, including, but not limited to:improve device control; to improve mapping of the region; to adaptcontrol system parameters (whether kinematic and/or solid mechanicparameters); to estimate, plan and/or control reaction forces of thedevice upon the anatomy; and/or to even monitor the systemcharacteristics for determination of mechanical problems. Alternatively,or in combination, shape information can be useful to simply visualizethe tool with respect to the anatomy or other regions whether real orvirtual.

In many conventional systems, the catheter (or other shapeableinstrument) is controlled in an open-loop manner, as described in U.S.patent Ser. No. 12/822,876, the contents of which are incorporated byreference in its entirety. However, at times the assumed motion of thecatheter does not match the actual motion of the catheter. One suchreason for this issue is the presence of unanticipated or unmodeledconstraints imposed by the patient's anatomy.

Thus to perform certain desired applications, such as, for example,instinctive driving, shape feedback, and driving in a fluoroscopy viewor a model, there exists a need for tool sensors to be properlyregistered to the patient in real time. Moreover, there remains a needto apply the information gained by spatial information or shape andapplying this information to produce improved device control or improvedmodeling when directing a robotic or similar device. There also remainsa need to apply such controls to medical procedures and equipment.

SUMMARY

A robotic system for manipulating a tool with respect to a target spaceis disclosed herein. The tool comprises a sensor coupled thereto. Thesystem comprises a robotic drive system and a controller. The roboticdrive system comprises at least one actuator and is configured to couplewith the tool to position the tool with respect to the target space. Thecontroller is configured to use a registration between a sensor frameand a target space frame such that the controller can direct the roboticdrive system in the target space frame using the registration. In someexemplary arrangements, the controller is configured to combine aplurality of discrete registrations to produce a combined registrationbetween the sensor frame and the target space frame.

Other and further exemplary configurations and advantages thereof willbecome apparent from the following detailed description when read inview of the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a variation of a localization system in a typicaloperation room set up.

FIG. 1B illustrates a 3D Model frame.

FIG. 2 illustrates an exemplary robotic surgical system.

FIG. 3 is a schematic representation of a first registration techniqueof correlating a sensor reference frame to selective reference frames.

FIG. 4 is a flow chart that illustrates a method of transforming areference frame for a sensor of a surgical tool into a target referenceframe.

FIG. 5 is a flow chart that illustrates a method of transforming areference frame associated with a tool into a target reference frame.

FIG. 6 is a flow chart that illustrates a method of transforming areference frame associated with a tool into a target reference frameutilizing medical appliances.

FIG. 7 is a flow chart that illustrates a method of using a sensor totransform a reference frame associated with a tool into a targetreference frame.

FIG. 8 is a schematic illustration of a method of using an intravascularimaging sensor coupled with a shape sensor to transform a referenceframe associated with a tool into a target reference frame.

DETAILED DESCRIPTION

Various localization systems and methods for tracking an elongateinstrument or tool, e.g., a robotically controlled elongate instrument,in real time, in a clinical or other environment, are described herein.The term “localization” is used in the art in reference to systems fordetermining and/or monitoring the position of objects, such as medicalinstruments or tools in a reference coordinate system. Variousinstruments are contemplated for use in the various systems describedherein. In one exemplary arrangement, elongate instruments arecontemplated, such as, e.g., a catheter or vascular catheter. Thevarious methods and systems may include integrating or registering alocalization system or a localization sensor coupled to a surgical tool,with an image. A fiber optic tracking or localization system is justone, non-limiting example of a system that allows for the tracking of alocation, position and/or orientation of a localization sensor placed.Various other localization sensors may be utilized, e.g.,electromagnetic sensors, and other sensors for detecting or controllingthe movement of medical equipment. When the localization sensor isintegrated into an image, it enhances the capabilities of an instrumentcontrol or tracking system by allowing a user or doctor to easilynavigate the instrument through the complex anatomy without exposing thepatient to excessive radiation over a prolonged period of time.

The localization data or tracking information of a localization sensormay be registered to the desired image or model to allow for navigationof an elongate instrument through the image or model to accuratelyrepresent movement of the elongate instrument within a patient.Registration is a process that requires relating a reference frame of asensor to another reference frame of interest. If the positions,orientations or shapes of two or more objects are known in the samereference frame, then the actual positions, orientations or shapes ofeach object relative to each other may be ascertained. Thus, with thisinformation, one can drive or manipulate one of the objects relative tothe other objects.

In most interventional procedures, the reference frame of interest isthe visualization frame. The reference frame is the frame that thedoctor is viewing, such as a patient or a live 2D/3D image suchfluoroscopy, ultrasound or others. Thus, the goal of registration is todetermine the relationship of a frame of a sensor integrated into a toolor element in the surgical suite within the frame of reference of thepatient, as represented in a 2D/3D image.

When the tool is registered to a 3D model, the user can drive andmanipulate the tool in the 3D model. This technique provides anadvantage in that there is no longer a need for live fluoroscopy andradiation during a procedure. The tool is localized to the 3D model andthe position, shape and orientation of the tool is visible to the user.Since the tool position, shape and orientation is updated real time by alocalization sensor, an image of the tool in the virtual representationof the 3D model will be updated as it is being advanced into thepatient. The sensor is localized to the reference frame of the 3D model;therefore the orientation of a tip of the tool is known relative to the3D model. This enables driving of the tool (such as a catheter) with 3dimensional views of the anatomy and hence improves visualization andcontrol during a surgical procedure.

However, many localization sensors are incremental measurement sensors,where the position and orientation of a particular point is calculatedand dependent on the previously calculated orientation andpositions/point spacings. Thus, the localization sensor operating in anymedical system needs to be registered with a coordinate system, frame orimage that is useful to an operator, such as the pre-operative 3D modelor a fluoroscopic image. For incremental measurement sensors, suchregistration is challenging because the coordinate system or frame ofthe sensor is not always easily related to the coordinate system ofinterest (i.e., the pre-operative 3D model).

Moreover, the relationship between the sensor and the coordinate systemof the interest may change over time during a procedure. For example, inone exemplary robotic system, a fiber optic sensor may have itsreference frame based physically in a splayer for a catheter. Thus, asthe splayer is robotically driven during a surgical procedure, theposition and orientation of the bases of the fiber will change withrespect to other reference frames.

In addition to changing positions of reference frames, the registrationprocess often requires information about the imaging system providingthe image, such as its physical dimensions and/or the details about theimaging techniques used to acquire a particular 3D model or other image.Due to the variability in equipment used in a clinical environment, incertain situations there may be no guarantee that such information willbe available or easily obtainable to an outside party.

As such, various techniques to estimate system parameters and variousregistration techniques may help facilitate the clinical use oflocalization technology.

In certain variations, a method for tracking a robotically controlledelongate instrument in real time may include displaying an image of apatient's anatomy. A localization sensor may then be coupled to therobotically controlled instrument. The localization sensor may providelocalization data of the sensor and/or instrument. Moreover, differentsensors may be registered to specific tools, thereby enabling tooldifferentiation. The localization data from the localization sensor maybe registered to the image. Registering may include transforminglocalization data generated by the localization sensor to the coordinatesystem or frame of the image such that localization data of the elongateinstrument, to which the localization sensor is coupled, is overlaid onthe image. The coordinate system of the localization sensor may betransformed or translated to the coordinate system of the image throughone or more transformations, and optionally through other coordinatesystems, to register the localization data to the image. As a result, acontinuously or substantially continuously updated location of at leasta portion of the elongate instrument is provided in the image of theanatomy of a patient, which allows for or facilitates robotic navigationor control of the elongate instrument through the anatomy e.g., throughthe vasculature of a patient.

The location, position and/or orientation of the localization sensor maybe continuously tracked to allow for accurate manipulation of theelongate instrument in or through the anatomy of a patient. Varioustypes of images may be utilized in the methods and systems describedherein. For example, an image may be generated by CT or 2D or 3Dfluoroscopy. An image may include a 3D or 2D anatomical model or a 2D or3D fluoroscopic image or other types of images useful for visualizing ananatomy of a patient to perform various medical procedures.

When using a fluoroscopy image, an image intensifier may be utilized.Localization data from the localization sensor may be registered to afluoroscopy coordinate system of a fluoroscopy image coupled to theimage intensifier. In order to register the localization data from thelocalization sensor to the fluoroscopy image, various parameters may beascertained or known. For example, such parameters may include: adistance from an X-ray source to the image intensifier, a distance fromthe source to a bed, a size of the image intensifier, and/or the axis ofrotation of a C-arm of the fluoroscopy system.

In certain variations, localization data can be registered to a 3Danatomical model or a fluoroscopy image. The techniques used to performthe registration vary depending on the target. Where localization datais registered to a fluoroscopy image, the 2D nature of the fluoroscopyimages may require that multiple images be taken at different anglesbefore the registration process is complete.

FIG. 1A is a schematic of a typical operation room set up for a roboticsurgical system. More specifically, a typical robotic surgical system 10includes a table 12 upon which a patient 14 will be placed, afluoroscopy system 16, and a surgical tool, such as a catheter 18 (bestseen in FIG. 2). Attached to the table 12 is a setup joint arm 20 towhich a remote catheter manipulator (RCM) 22 is operatively connected. Asplayer 24 may be mounted to the RCM 22. A surgical tool, such as acatheter, is operatively connected to the splayer 24. A fiber sensor 26may be operatively connected to the surgical tool. The fluoroscopysystem 16 includes a C-arm 28. A fluoroscopy panel 30 is mounted to theC-arm 28. The C-arm is selectively moveable during the procedure topermit various images of the patient to be taken by the fluoroscopypanel 30.

Additional portions of the robotic surgical system 10 may be furtherseen in FIG. 2. More specifically, robotic surgical system 10 mayfurther comprise an operator control station 31, which may be remotelypositioned with respect to table 12. A communication link 32 transferssignals between the operator control station 31 and the RCM 22. Theoperator control station 31 includes a control console 34, a computer36, a computer interface, such as a mouse, a visual display system 38and a master input device 40. The master input device 40 may include,but is not limited to, a multi-degree of freedom device having multiplejoints and associated encoders.

Each element of the robotic surgical system 10 positioned within theoperating suite may define a separate reference frame to which sensorsmay be localized. More specifically, separate reference frames may bedefined for each of elements of the robotic surgical system 10. Suchreference frames may include the following: a table reference frame TRFfor the table 12, a setup joint frame SJF for the setup joint 20, an RCMreference frame RRF for the remote catheter manipulator (RCM) 22, asplayer reference frame SRF, a fluoroscopy reference frame FF. Separatereference frames may also be defined for a patient-patient referenceframe PRR, a reference frame FRF for a sensor disposed within a surgicaltool, and a pre-operative 3D frame AMF (best seen in FIG. 1B).

To relate a coordinate frame of a fiber optic sensor of a tool to eithera fluoroscopy frame FF, or a pre-operative 3D frame AMF, a varietyregistration techniques is proposed herein. Generally, the techniquesproposed herein fall into several categories. A first category involvesusing image processing or vision techniques to relate a reference frameRFR of a fiber sensor directly to an image or 3D model. This techniquemay be accomplished manually by a user or done automatically using imageprocessing techniques. Another category to coordinate the referenceframe FRF of a fiber optic sensor involves using knowledge abouthardware, and potentially other sensors and or position of the fiber.Further discussion of these techniques is set forth below.

Registration to Fluroscopy Coordinate Frame

Referring to FIG. 3, the first category of registration techniques willnow be described. The first category relates the coordinate system ofthe sensor reference frame FRF to a fluoroscopy reference frame FFdirectly. This technique utilizes fluoroscopy images taken during thesurgical procedure by the fluoroscopy system 30, in real-time.

More specifically, an exemplary registration process 200 is illustratedin the flow chart of FIG. 4. The process 200 begins by inserting a tool202 into a patient. As described above, in one exemplary configuration,the tool 202 is a catheter 18, which may be inserted by an RCM 22. Next,in step 204 an intra-operative image is taken of the tool 18.

In one exemplary arrangement, the intra-operative image is a fluoroscopyimage taken by fluoroscopy system 30. Next, distinctive elements of thetool are identified in the fluoroscopy image in step 206. In oneexemplary configuration, the identification step 206 may be accomplishedby instructing the user to select certain marked points of a catheter 18in the fluoroscopy image at the work station 31. Examples of markedpoints include, but are not limited to, physical features of thecatheter 18 such as the tip of the catheter 18, certain shapes and anarticulation band. In other exemplary configurations, fluoroscopymarkers may be disposed on the catheter.

Once the selected points are identified in the fluoroscopy image, in thenext step 208, coordinates of the selected points of the catheter 18 maybe compared to corresponding measured points of elements of thecatheter. In one exemplary configuration, measured points from a toolsensor operatively connected to the tool 18 may be used. Morespecifically, in one exemplary configuration, the tool sensor is a fiberoptic sensor. Information about the fiber optic sensor will be known inrelation to the features on the catheter from an in-factory calibration.This comparison can be used to determine a transformation matrix thatcan be used to transform a reference frame FRF for a sensor disposedwithin the surgical tool to into the fluoroscopy reference frame FF.This transformation then localizes the tool relative to theintra-operative fluoroscopy image.

Once the fiber sensor of the tool has been registered or localized tothe fluoroscopy image, the tool operator can now move or drive the toolto various, desired points visualized in the fluoroscopy image.Moreover, the computer 36 may be configured to track the marked pointsover time, such that an appropriate transformation may be updated.

In one exemplary configuration, the identifiable markers need not be onthe portion of the tool that is inserted into the patient. For example,markers may be embedded on a splayer 24, which may allow for larger andmore complex markers to provide enhanced registration capabilities.

As described above, in addition to utilizing fluoroscopy marked points,it is also contemplated that distinct shapes that may be visible underfloursocopy may also be used. However, this technique will require someimage segmentation.

With respect to the proposed technique of localizing a sensor referenceframe FRF to the fluoroscopy reference frame FF, the localization sensorcould serve to reduce the use of fluoroscopy during a procedure. Morespecifically, use of fluoroscopy will only be required whenre-registration appears to be required from the captured image and thedata obtained from the sensor if the accuracy of the registration needsto be improved at any point during the procedure.

In certain arrangements, it may be desirable to further register thetool to a 3D model reference frame AMF, as illustrated in FIG. 3.Registration to the 3D Model is discussed more fully below.

Registration Through Successive Physical Components

Another technique proposed to register a tool 18 to a desired referenceframe involves the use of physical components of the medical system 10and multiplying successive transformations. This proposed technique 300is illustrated schematically in FIG. 5 and involves finding atransformation path from a tool reference frame such as a fiber sensor,splayer 24, or catheter 18, to the table 12, as in most surgical suitesetups, the table location is generally known with respect to thefluoroscopy system 30. More specifically, registration technique 300involves determining a tool reference frame 302 (where the toolreference frame may be defined as the sensor reference frame FRF,splayer reference frame SRF or a catheter reference frame) andcorrelating the tool reference frame to a table reference frame TRF in asecond step 304, thereby registering the tool 18 to the table 12.Registering the tool 18 to the table 12 will serve to provide necessaryinformation to permit registration to an additional target frame, suchas a fluoroscopy reference frame FF, for example. Because the table 12location is typically known with respect to a fluoroscopy system 30,once the tool 18 is registered to the table reference frame TRF, acomparison of set reference points of the table 12 with correspondingreference points in a fluoroscopy image may be used to determine atransformation matrix to transform the table reference frame TRF intothe fluoroscopy reference frame FF. This transformation then localizesthe tool relative to the intra-operative fluoroscopy image.

However, it is understood that the present disclosure does not requirethat the tool 18 be registered to the table 12. Indeed, it is expresslycontemplated that registration of the tool 18 to other physicalcomponents within the surgical suite may also be utilized. This proposedtechnique requires the use of other sensors in addition to, oralternative to a fiber sensor, however. Exemplary configurations ofregistration through physical surgical suite components is are discussedin further detail below.

One exemplary method of performing registration through successivephysical components is illustrated in the flow chart in FIG. 6. In thistechnique, the registration process 400 begins with the step 402 ofdetermining the location of the setup joint 20 with respect to the table12. Encoders on the RCM 22 and setup joint 20, with kinematic models maybe used to determine the location of the setup joint 20 with respect tothe table 12. More specifically, the encoders assist with determiningthe location of the RCM 22 with respect to the table 12. With thelocation value of the position that the setup joint 20 is fixed to thetable 12, the location of the splayer carriage 24 carried by the RCM 22with respect to the table 12 can be determined; i.e., the setup jointreference frame SJF is localized with the RCM reference frame RRF.Because information about the catheter will be known in relation to thesplayer carriage 24 from an in-factory calibration, in step 404 of theregistration process 400, a comparison of the splayer carriage 24information with the can be used to determine a transformation matrixthat can be used to transform the splayer carriage reference frame SRFto the table reference frame TRF. As described above, because the table12 location is known with respect to the fluoroscopy system 30, in step406 another transformation may be done from the table reference frameTRF to the fluoroscopy reference frame FF. This final transformation,i.e., from the table reference frame TRF to the fluoroscopy referenceframe FF, then localizes the tool relative to the intra-operativefluoroscopy image.

In another exemplary method of performing registration throughsuccessive physical components, inertial sensors on the RCM 22, coupledwith the information about the initial position of the RCM 22 on thetable 12, may be used to assist in localizing the catheter splayerreference frame SRF to the table reference frame TRF. More specifically,once the RCM 22 is localized to the table reference frame TRF, thecatheter splayer reference frame SRF may be localized to the tablereference frame TRF, as the position of the catheter splayer 24 withrespect to the RCM 22 will be known from in-factory calibration.

Yet another exemplary method 500 of performing registration throughphysical components is illustrated in FIG. 7. The method 500 uses asecond fiber optic sensor. In a first step 502, one end of the fiberoptic sensor is fixed to the table 12. Next, in step 504, the other endof the sensor is fixed to the splayer 24 in a knownorientation/position. In this technique, a position and orientationtransformation between the tip and base of the fiber sensor may bedetermined, thereby localizing the catheter splayer reference frame SRFto the table reference frame TRF in step 506. However, it is understoodthat the initial position of the fix point at the table must be known.Once the catheter splayer reference frame SRF is localized to the tablereference frame TRF, because the table 12 location is known with respectto the fluoroscopy system 30, in step 508 another transformation may bedone from the table reference frame TRF to the fluoroscopy referenceframe FF. This final transformation, i.e., from the table referenceframe TRF to the fluoroscopy reference frame FF, then localizes the toolrelative to the intra-operative fluoroscopy image.

A further exemplary method of performing registration of a surgical toolto a physical component includes using electromagnetic sensors to trackthe location of the splayer 24 with respect to an electromagnetic sensorat a known location on the table 12. In using this technique, becausethe tool location is calibrated to the splayer 24 in the factory, oncethe splayer 24 is localized to the table reference frame TRF, the toolmay be localized to the fluoroscopy reference frame FF as the table 12is known with respect to the fluoroscopy system 30.

In yet another exemplary method, instead of electromagnetic sensors,overhead cameras or other visualization techniques may be employed totrack distinct features on the splayer 24 and the table 12 to determinethe respective orientation and position with regard to each other.

A further technique may use the range sensors (such as, e.g., IR orultrasound) to find the distance to several distinct and predeterminedpoints on the table 12 and the splayer 24. Once the splayer 24 islocalized to the table reference frame TRF, the tool may be localized tothe fluoroscopy reference frame FF as the table 12 is known with respectto the fluoroscopy system 30.

All of the above techniques serve to register the tool to a physicalcomponent within the surgical suite, such as, for example, the table 12.Some of the above techniques require the RCM 22 and setup joint 20 to beregistered to the table 12. That pre-registration step may be achievedby using some known feature on the table 12 that the setup joint 20 mayreference. In another exemplary configuration, the tip of a sensorequipped tool may be used to touch or register the known feature on thetable 12 to locate the table 12 with respect to other equipment withinthe surgical suite.

The kinematics of the RCM 22 can also be calculated by holding the tipof a fiber optic equipped tool in an arbitrary fixed location andcycling through the various axes of the RCM 22. By keeping the tip in afixed location, the relative changes to the fiber origin can beobserved, and thus the kinematics of the system can be determined andlocalized to the table 12. Once localized to the table reference frameTRF, the tool may then be localized to the fluoroscopy reference frameFF, as discussed above.

In addition to adding the sensors discussed in the above techniques,additional modifications may be made to the location of the fiber baseto facilitate registering the fiber sensor to the physical structurewithin the suite, such as, for example, the table 12. For example, onemodification is to extend the length of a fiber in the catheter so thatthe origin/base can be extended out of the splayer 24 and attached to afixture having a known location on the table 12. Once localized to thetable reference frame TRF, the tool may then be localized to thefluoroscopy reference frame FF, as discussed above.

Registration to a 3D Model

Registration of the tool to a 3D Model is also contemplated in thisdisclosure. Such registration may be performed directly from the fibersensor reference frame FRF to the 3D Model frame AMF. In one exemplarytechnique, the operator is utilized. When the tool (such as thecatheter) is inserted into the patient, tortuosity can be visualizedfrom the fiber sensor data, as well as on the pre-operative 3D Model. Toregister the tool in the 3D Model, the operator may translate and rotatethe 3D Model so that distinct images and/or features in the tortuositymatch or line up with the shape of the fibers. However, in using thistechnique, every time the patient moves, the tool should bere-registered.

In another exemplary arrangement, rather than have an operator manuallymatch features in the tortuosity, in one technique, a computer algorithmsuch as automated geometric search or mathematical optimizationtechniques that segments the model and matches the model and tool shapedynamically may also be used to match various shapes or features fromthe fiber sensor to the 3D preoperative Model. However, if the patientmoves, even slightly, the 3D Model could be mis-registered. Thus, thealgorithms may be used to re-register the tool automatically or the usercould use an input device, such as a track ball or mouse to move the 3DModel manually.

Another proposed technique may be used to register the fiber sensor tothe 3D Model through the fluoroscopy image, as illustrated in FIG. 3. Inthis technique, any of the above described techniques for registeringthe surgical tool 12 to the fluoroscopy reference frame FF may beutilized. To register the fluoroscopy reference frame FF to the 3D Modelreference frame AMF, in one exemplary configuration, specific anatomicallandmarks may be used to provide recognizable reference points. The onlyrequirement for this approach is to have an anatomical landmark that isrecognizable in both the fluoroscopy reference frame FF, as well as thepre-operative 3D Model reference frame AMF. Once the recognizable pointis identified in the fluoroscopy image, the 3D Model may then by rotatedby the operator to line up the recognized points in the fluoroscopyimages with the 3D Model images. This action serves to register thefluoroscopy reference frame FF to the frame of the 3D Model AMF. As thetool has previously been localized to the fluoroscopy reference planeFF, so now once the fluoroscopy reference plane FF is so registered, thetool's location within the patient's anatomy may be determined withreference to the 3D Model. Thus, the tool is localized to the 3D Model.In one exemplary configuration, a visual representation to the tool,based on the transformation matrix, may be displayed on the 3D Model. Inthis manner, the tool operator may then navigate the tool through the 3DModel.

While certain of the above described techniques utilized distinct markedpoints of a tool, such as a medical catheter, to register the tool withthe fluoroscopy image, it is also understood that registration of thetool may occur based on the location of the tool at the distinctanatomical landmarks. In other words, as the tip of the tool can bedriven to a known anatomical location in the patient, the 3D Model maythen be rotated by the user to overlay the known anatomical location inthe 3D Model with the fluoroscopy image, in which the known anatomicallocation is visible. Such action will also serve to register the toolwith the 3D Model or localize the tool in the reference frame of the 3Dmodel reference frame AMF.

In another exemplary configuration, instead of, or in addition to,having the user manually rotate the 3D Model to correspond with thefluoroscopy image to line up distinct landmarks visible in both thefluoroscopy image and the 3D Model, the computer 36 may be programmed toemploy a suitable algorithm such as automated geometric search ormathematical optimization techniques configured to match a distinctshape measured by the fiber sensor with a corresponding shape in the 3DModel. In this manner, the tool may also be registered with the 3DModel. The accuracy of this method will depend on the size of vesselthat the tool is in, and the degree of curvature of the tool. Accuracywill be improved if the tool is in a smaller vessel and will be worse ifthe tool is in larger vessels. This automated technique can also be usedin conjunction with the manual techniques described above. For example,the computer may be programmed to do automatic registration and suggesta preferred registration but the user may do final adjustments of themodel. Once the tool is localized in the 3D Model of the patient'sanatomy, the user may then proceed to maneuver the tool in the 3D Model.

Another technique that may be utilized to register the tool to the 3DModel through fluoroscopy system 30 involves the use of radiopaquemarkers. More specifically, radiopaque markers can be fixed to theanatomy. However, these markers would need to be present duringpreoperative imaging when the 3D Model is created, and remain in thesame location during intraoperative fluoroscopy imaging. With thistechnique, the position of these markers in the fluoroscopy referenceframe FF can be used to correlate to the same markers in the 3D Modelreference frame AMF, thereby registering the fiber sensor to the 3DModel reference frame AMF.

Another technique that may be utilized to register the surgical tool toa 3D Model utilizes intravascular imaging. This technique allows for 3Dvisualization of a surgical tool, such as, a catheter, in the anatomy,but without the use of fluoroscopic imaging. Such a technique canbenefit both physicians and patients by improving the ease of toolnavigation, as well as and reducing radiation exposure of personnelinside the operating room.

The registration technique 600 begins by utilizing a sensor 602operatively coupled to the tool to sense a shape of the tool 604 whilein the patient. This sensed shape is then mathematically correlatedagainst features of the vascular model such as centerlines or walls inwhich a larger correlation value corresponds to a better match. Thecorrelation can be performed in real-time on each shape or by batchprocessing a sequence of shapes. This proposed technique assumes thatthe tool will always follow a unique configuration through thevasculature, and thus, a global maximum for the correlation exists.However, the correlation may return many local maxima since the toolconfiguration may follow many different paths between fixed distal andproximal ends. Choosing an incorrect maximum introduces registrationerror. Furthermore, in some cases, the pre-operative 3D model may differfrom the actual vasculature for a number of reasons, including, forexample, patient motion or inaccuracies in pre-operative sensing. Suchsituations also may lead to registration error.

Recent advances in intravascular imaging technology have brought aboutsensors 604 that can provide information about the local structure ofvessel walls 606. Such information may be used for shape registrationand environmental mapping. Two examples of these sensors areintravascular ultrasound (NUS) probes, and optical coherence tomography(OCT). Intravascular ultrasound periodically produces a 2-Dcross-sectional view of the blood vessel either to the sides of thecatheter in standard NUS or to the front of a catheter in Forward-FacingIVUS. Optical Coherence Tomography periodically produces a local 3D viewof the vessel into which the tool is inserted. The images produced bythese technologies may be processed to provide an estimate of a curve orsurface representing the vessel wall 606. The sensors 604 may alsodetermine the location of the catheter's endpoint within the vascularcross-section. Use of the sensors coupled with the tool 602 to provideshape information coupled with information obtainable from sensors 604configured to provide information about the vessel walls 606 can assistin defining the 3D shape of the blood vessel 608.

Once the shape of the vessel is defined or otherwise reconstructed usingthe combined sensor data, the shape can be mathematically correlated tothe 3D model 610, thereby registering the tool to the 3D Model 612. Inimplementation, the 3D reconstruction and correlation steps may becombined into a single recursive filtering algorithm. A Bayesian filter(e.g. Kalman Filter (EKF), Unscented Kalman Filter (UKF), or ParticleFilter) may be used to develop an estimate of the tool's positionrelative to the pre-op 3D model given both imaging and sensor 602information. The filter's state is a set of points or a parametric curverepresenting the position and shape of the tool 602 with respect to thepre-op 3D model, as well as the velocity of this shape. For accurateregistration, patient motion may also be taken into account. Thus, thefilter's state may also contains warping parameters for the pre-op 3Dmodel. These warping parameters may be evenly distributed, or may beselected based on the structure of the anatomy around the vasculature.The motion of the structure of the anatomy around the vasculature may bemeasured using visible light tracking technologies such as stereoscopiccameras, structured light tracking technologies, and/or otherlocalization technologies attached to the patient skin.

The recursive filtering algorithm operates by predicting the motion ofthe tool in the 3D model, then performing an update of the filterhypothesis given new sensor measurements. At each time-step, a kinematicmodel of the catheter and control inputs such as current pull-wiretension and displacement may be used to perform the filter's motionupdate. The filter's measurement update may apply a correction to thetool registration and model warping parameters by comparing a predictedvessel wall with the sensed position and orientation of the vessel fromthe imaging and sensor measurements. The update effectively executes thecorrelation between 3-D sensor information and the 3D model. Performingthese correlations repeatedly in a recursive filtering framework mayprovide a real-time catheter position estimate. Furthermore, thefilter's parameters may be tuned such that differences between themeasurements and the model over a small time constant (ms) will lead tochanges in the catheter position estimate in order to filter outhigh-frequency sensor noise. Differences over a large time constant(seconds) may lead to changes in the model's warping parameters.

Thus, once the tool has been registered to the 3D model, the location ofthe tool within the 3D model may be determined, allowing an operator todrive the tool within the vasculature using the 3D model withoutrequiring intra-operative fluoroscopy.

Sensors 604 may also be utilized to sense the environment around thetool. Thus, once the tool is registered to the 3D the model, thisenvironmental information, such as, for example, vascular occlusions maybe displayed at the correct position in the 3D Model.

More specifically, after tool registration, the intravascular imagingsensor 604 provides a mechanism to sense and display features of theenvironment surrounding the tool without the use of fluoroscopy. Thereare many ways to display this information. One non-limiting option is tosimply provide a display of a real-time view of the imaging sensor'soutput alongside a view of the catheter's location in the 3D model orsuperimposed on top of the 3D model. Another option may be to analyzethe intravascular image to detect environmental changes. For example,IVUS image processing techniques can be used to detect areas of plaquein the image. This information can be used to annotate the IVUS image inorder to aleli the physician to environmental conditions. Since acombination of IVUS and sensor data 602 may provide 3D information onthe structure of these plaque formations, the 3D pre-op model can alsobe annotated. In this way, the existing work that has used IVUS toperform vascular sensing may be leveraged by the combined IVUS andsensor system to provide a 3D view of the environment to the physician.

Each of the individual variations described and illustrated herein hasdiscrete components and features which may be readily separated from orcombined with the features of any of the other variations. Modificationsmay be made to adapt a particular situation, material, composition ofmatter, process, process act(s) or step(s) to the objective(s), spiritor scope of the present invention.

Methods recited herein may be carried out in any order of the recitedevents which is logically possible, as well as the recited order ofevents. Furthermore, where a range of values is provided, everyintervening value between the upper and lower limit of that range andany other stated or intervening value in that stated range isencompassed within the invention. Also, any optional feature of theinventive variations described may be set forth and claimedindependently, or in combination with any one or more of the featuresdescribed herein.

All existing subject matter mentioned herein (e.g., publications,patents, patent applications and hardware) is incorporated by referenceherein in its entirety except insofar as the subject matter may conflictwith that of the present invention (in which case what is present hereinshall prevail). The referenced items are provided solely for theirdisclosure prior to the filing date of the present application. Nothingherein is to be construed as an admission that the present invention isnot entitled to antedate such material by virtue of prior invention.

Reference to a singular item, includes the possibility that there areplural of the same items present. More specifically, as used herein andin the appended claims, the singular forms “a,” “an,” “said” and “the”include plural referents unless the context clearly dictates otherwise.It is further noted that the claims may be drafted to exclude anyoptional element. As such, this statement is intended to serve asantecedent basis for use of such exclusive terminology as “solely,”“only” and the like in connection with the recitation of claim elements,or use of a “negative” limitation. Unless defined otherwise, alltechnical and scientific terms used herein have the same meaning ascommonly understood by one of ordinary skill in the art to which thisinvention belongs.

This disclosure is not intended to be limited to the scope of theparticular forms set forth, but is intended to cover alternatives,modifications, and equivalents of the variations described herein.Further, the scope of the disclosure fully encompasses other variationsthat may become obvious to those skilled in the art in view of thisdisclosure. The scope of the present invention is limited only by theappended claims.

While multiple embodiments and variations of the many aspects of theinvention have been disclosed and described herein, such disclosure isprovided for purposes of illustration only. Many combinations andpermutations of the disclosed system are useful in minimally invasivemedical intervention and diagnosis, and the system is configured to beflexible. The foregoing illustrated and described embodiments of theinvention are susceptible to various modifications and alternativeforms, and it should be understood that the invention generally, as wellas the specific embodiments described herein, are not limited to theparticular forms or methods disclosed, but also cover all modifications,equivalents and alternatives falling within the scope of the appendedclaims. Further, the various features and aspects of the illustratedembodiments may be incorporated into other embodiments, even if no sodescribed herein, as will be apparent to those skilled in the art.

The invention claimed is:
 1. A method of registering a tool of a roboticmedical system to a desired frame, the method comprising: tracking aposition of the tool of the robotic medical system using one or moresensors coupled to the tool; tracking a position of a physical componentof the robotic medical system using one or more sensors coupled to thephysical component; comparing a tool reference frame to a physicalcomponent reference frame to generate a registration of the tool to thephysical component; comparing the physical component reference frame toa visualization reference frame to generate a registration of thephysical component to a visualization of the anatomy; and determining alocation of the tool in the visualization of the anatomy based on theregistration of the physical component to the visualization of theanatomy and the registration of the tool to the physical component. 2.The method of claim 1, wherein at least one of the one or more sensorscoupled to the tool or the one or more sensors coupled to the physicalcomponent comprises an electromagnetic sensor.
 3. The method of claim 1,wherein at least one of the one or more sensors of the tool or the oneor more sensors of the physical component comprises a fiber sensor. 4.The method of claim 1, further comprising displaying the location of thetool in the visualization of the anatomy.
 5. The method of claim 4,wherein displaying the location of the tool in the visualization of theanatomy comprises overlaying localization data related to the tool onthe visualization of the anatomy.
 6. The method of claim 1, wherein thevisualization of the anatomy comprises a CT image.
 7. The method ofclaim 1, wherein the visualization of the anatomy comprises afluoroscopy image.
 8. The method of claim 1, wherein the visualizationof the anatomy is one of a pre-operative anatomical image or anintra-operative image.
 9. The method of claim 1, wherein the physicalcomponent of the robotic medical system is a table.
 10. The method ofclaim 1, wherein a location of the physical component with respect to avisualization system used to obtain the visualization of the anatomy isknown.
 11. The method of claim 1, wherein the tool is a catheter. 12.The method of claim 1, wherein the tool is a splayer.
 13. A method ofregistering a tool of a robotic medical system to a desired frame, themethod comprising: tracking a position of the tool of the roboticmedical system using one or more sensors coupled to the tool; tracking aposition of a physical component of the robotic medical system using oneor more sensors coupled to the physical component; comparing a toolreference frame to a physical component reference frame to generate aregistration of the tool to the physical component; comparing thephysical component reference frame to a visualization reference frame togenerate a registration of the physical component to a visualization ofthe anatomy; and displaying a location of the tool in the visualizationof the anatomy based on the registration of the physical component tothe visualization of the anatomy and the registration of the tool to thephysical component.
 14. The method of claim 13, wherein at least one ofthe one or more sensors coupled to the tool or the one or more sensorscoupled to the physical component comprises an electromagnetic sensor.15. The method of claim 13, wherein at least one of the one or moresensors of the tool or the one or more sensors of the physical componentcomprises a fiber sensor.
 16. The method of claim 13, wherein displayingthe location of the tool in the visualization of the anatomy comprisesoverlaying localization data related to the tool on the visualization ofthe anatomy.
 17. The method of claim 13, wherein the visualization ofthe anatomy comprises a CT image.
 18. The method of claim 13, whereinthe visualization of the anatomy comprises a fluoroscopy image.
 19. Themethod of claim 13, wherein the visualization of the anatomy is one of apre-operative anatomical image or an intra-operative image.
 20. Themethod of claim 13, wherein the physical component of the roboticmedical system is a table.
 21. The method of claim 13, wherein locationof the physical component with respect to visualization system used toobtain the visualization of the anatomy is known.
 22. The method ofclaim 13, wherein the tool is a catheter.
 23. The method of claim 13,wherein the tool is a splayer.